Washington -LRB- CNN -RRB- -- Army Master Sgt. Benjamin A. Stevenson , 36 , was on his 10th tour of duty in the war zones of Afghanistan and Iraq when he was killed Thursday in a remote area of eastern Afghanistan .

Few details are available on the circumstances that led to the death of the highly decorated soldier , from Canyon Lake , Texas .

However , a U.S. military official has now confirmed to CNN that Stevenson was the only U.S. casualty of a brutal two-day firefight against an al Qaeda-related group that erupted when U.S. and Afghan troops attacked an insurgent encampment , killing nearly 80 foreign fighters .

That single piece of information is a rare glimpse into the world of U.S. special operations forces who have done more tours than most in the last decade . Special forces tours of duty typically last six to eight months , compared to regular combat tours of one year . Many troops have spent more time away from home than at home , but little is said about what they do these days in fighting insurgent strongholds .

The official who confirmed Stevenson was part of this raid declined to be named because he was discussing the Army 's Special Operations Command .

Stevenson was part of a U.S. and Afghan special operations mission that went in to attack the area in Afghanistan 's Paktika province .

The camp they attacked and the fighters there were part of the so-called Haqqanni network , which is responsible for many recent attacks in Afghanistan and is closely tied to al Qaeda . The Haqqanis traditionally rely on Afghan and Pakistani fighters , but in this instance most of the fighters there who were killed were Arabs and Chechens , brought into Afghanistan from Pakistan .

That alone is a worrisome trend . A second U.S. military official tells CNN that the US is seeing the Haqqanis increasingly turn to foreign fighters they bring into Afghanistan .

`` This is how they are expanding their capabilities , '' the official said . The U.S. believes this camp was an assembly and training point for these foreign fighters to stage attacks across Afghanistan .

During the two-day firefight against the camp , the U.S. troops found several caves and fortified bunkers . Airstrikes were called in using missile-equipped helicopters , fighter jets dropping precision weapons and unmanned drones .

Coalition forces were led to the camp by former insurgents , but it 's not clear if the extent of the opposition was immediately clear to the coalition .

When the dust finally cleared , Stevenson was the only fatality . The U.S. military , still cloaked in secrecy , wo n't say how he perished .

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Man who died in firefight was on 10th tour of duty

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Al Qaeda-linked group has expanded its network of fighters

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Special ops forces tend to do more tours than other divisions

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U.S. remains tight-lipped about special ops